How Miso is Made

Ever wonder what miso is? If you’ve been to Japan or eaten at a Japanese restaurant, you’ve likely had or at least seen miso. I remember my first time having miso soup. I was in college trying out a little Japanese restaurant that had popped up just outside the UofA. I was pretty green as far as Japanese food went so I ordered teriyaki chicken (I’m sure the chef was thinking all kinds of bad things about me). Before the meal, a bowl of soup appeared. It was a clear broth with some kind of brown particles floating in it. I tried the soup, but the flavor was so different from anything I had eaten before. I didn’t really enjoy it, but then it quickly grew on me. Now, I look forward to miso, be it in my soup, as a glaze for fish, or in the middle of a rice ball.

I’ve studied Japan for a long time, and for most of that time I’ve always translated miso as ‘fermented soy bean paste.’ Just like soy sauce, miso is made from soy, but that is only part of the story. A few weeks ago, my island had its sangyo matsuriwhere I was able to meet one of the people who make miso here (Kumejima‘s miso is quite popular). I was interested in the process so I wrangled a visit to the factory.

One of the first things I found out is that they don’t make miso all the time. Traditionally, miso was something made at home. Each family would make their own miso for their own use. As with so many things, the miso making skills are fading with the convenience of store-bought foods. Still, there are a few places that still do local miso. Since it is a fermented product, the temperature is an important factor, thus miso can only be made in moderate seasons. If it gets too cold, or too hot, the fermentation wont go on as well.

The process also takes more than three months. At the small local factories, they make large batches two or three times a year as needed. The rest of the time, they focus on other projects or on creating new items.

Day One

I was actually shocked to learn that miso is mostly rice and has few other ingredients. Overall, only boiled rice, soybeans, salt, and koujikin make up the delicious, umami food that is such a huge part of Asian cooking.

On the first day of production, large amounts of rice are steamed. At Aguritto, the factory I visited, they use two large boiler/box steamers to steam 35kg of rice in two batches. The rice takes about two hours to steam, after which it is removed to large wooden trays with blanket linings that absorb excess water to cool. These blankets replace the rice stalks that were traditionally used. Once the rice has cooled, the koujikin is added. Koujikin is a fungus (Aspergillus oryzae) that acts as the catalyst in the fermentation of many Japanese foods and alcohol. It replaces the human saliva originally used to make sake. The rice is bundled into the blankets and left to dry and ferment for two days.

Day Two

The second day of work on a miso batch starts three days after the rice is cooked. Roughly 2/3 the amount of beans are used in relation to the rice. they are also steamed then cooled. The beans are sent through a large grinder to process them. The fermented rice is also removed from storage and broken up into manageable batches.

Once everything is prepared, each rice batch is added to a drum mixer with salt and a measure of the processed beans. Once everything is well mixed, it is packed into containers and sealed against the air. These packages are left in a dark area for two to three months to ferment.

There are many kinds of miso, all with different purposes. The color and flavor of the miso changes with the time allotted for fermentation. The miso made in the video is for soup and will end as a light brown. The picture to the left is a much darker version used in cooking that has fermented far longer.

Aguritto’s miso is just one of several companies that produce miso on the island. Some households still make their own since it is a simple process (though it requires significant planning and patience). This company has only been making miso for about two years, based on Fujiko-oba’s recipe. I made an advanced miso soup recipe that turned out very well, and I can attest that local will likely beat out the major brands any day.

Thanks for commenting! After spending so many years eating the stuff I figured I should find out what is actually in the stuff. Turns out to be pretty interesting!

Welcome to More Things Japanese, a blog devoted to bringing you interesting insights into life in Japan. I post each week on Japanese culture, food, and more! I'm also the author behind the Samurai Awakening book series and Kumeguide.com.
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